<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>权重叠加-第一题</title>
  <style>
    /* 0,0,2,1 */
    .c1 .c2 div {
      color: red;
    }

    /* 0,1,0,1 */
    div #box3 {
      color: aqua;
    }

    /* 0,1,1,0 */
    #box1 .c3 {
      color: orange;
    }
  </style>
</head>

<body>
  <div id="box1" class="c1">
    <div id="box2" class="c2">
      <div id="box3" class="c3">这行文本是什么颜色？</div>
    </div>
  </div>
</body>

</html>